The present invention relates to electronic locking systems, and more particularly to electronic locking systems of a type including a reprogrammable key which electronically and mechanically interacts with a reprogrammable lock cylinder.
Electronic security systems have been well known for a number of years, and recent years have seen the marriage of electronic technology with traditional door locking devices such as mortise locks. Some of the early commercial systems have required a hard-wired connection between a central processor and the electronics of the locking systems of given doors. A disadvantage of such systems is the requirement of cable connections between the central controller and individual lock assemblies. This requires expensive remodelling, and such installations are vulnerable to tampering.
Other systems integrate hardware elements for control of functions of locking systems within the lock assembly itself, typically by housing circuit boards, power supplies, etc. within the door or in a module attached to the door. This approach also requires considerable remodeling of the installations to adapt to the specifications of the given locking systems. There is a need for improved locking systems which permit retrofitting of locking assemblies of a type compatible with traditional installations, thereby facilitating the conversion from traditional mechanical locking systems to electronic locks.
The use of innovative techniques for coding locks, such as for example optical, magnetic, electronic, and other techniques, offers the possibility of a number of significant advantages as compared with mechanical bitting. Electronic coding and the like holds the promise of increased information content with attendant improvements to system capabilities; the flexibility of recoding the cylinder or key (or both); networking with other electronic systems of an installation; effective new countermeasures against "lock-picking" attempts; and developments of versatile management systems for hotels and other institutions. Prior art electronic locking systems have just begun to realize some of these advantages, and are hindered by limitations on the loads of information in change between key and lock.
U.K. Patent Application No. GB 2112055A and Australian Patent Application No. AU-A-21588/83 disclose combination mechanical/electronic lock cylinders including a "rotor" (cylinder plug) and "stator" (cylinder shell). The stator houses a solenoid-actuated locking bolt which is oriented parallel to the keyway and which has a retaining member at one end. The retaining member mates with a grooved blocking member fixed to the rotor, the cam groove being profiled to include a "locking notch" (in 2112055A) or "retaining rings" (in 21588/83) which prevent rotation of the rotor in certain states of the solenoid.
U.K. Patent Application No. GB 2155988 A discloses a mechanical/electronic key in which an electronic assembly (such as a dual-in-line standard package integrated circuit) is mounted in a casing which serves as the key grip. The casing is fixed to the key shank and includes a connecting part for electrical contacts. This application does not show the use of electronically eraseable programmable read-only-memory (EEPROM) for strong keying code, nor the mounting of an IC directly to the key shank.
It is a primary object of the invention to provide an electronic door locking system type including a self-contained lock cylinder. A related object is to design a system of this type which is compatible with pre-existing mechanical lock installations, facilitating conversion from mechanical to electronic looks.
Another object of the invention is to design a reliable locking system. Such system should avoid failures due to a variety of physical conditions, such as mechanical stresses, poor eletronic connections, and electrostatic discharges.
Desirably such system should be a purely electronic one, i.e. not dependent on mechanical bitting or the key to open the lock cylinder.
Still another object is to provide the ability to electronically transfer information from the key to the cylinder, and from the cylinder to the key. A related object is to permit recoding of the cylinder by the key, and vice versa. Such a system should be versatile in operation, allowing multilevel master keying and a variety of other significant keying functions.
The invention adapts to an electronic lock comprising a housing, and a plug supported for rotation within the housing and having a keyway to receive the blade of a key which rotates the plug during operation of the locking apparatus. A locking member is movable into engagement with the plug to prevent the movement of the plug and the operation of the locking apparatus and movable out of engagement with the plug to allow the rotation of the plug and the operation of the locking apparatus. A solenoid having a core coupled to the locking member moves the locking member into and out of engaement with the plug. A permanent magnet is movable between a first position to receive and hold the solenoid core to maintain the locking member out of engagement with the plug, and a second position to release the solenoid core, and a driving means moves the magnet in at least one direction between the first and second positions.
Consequently, power may be turned off to the solenoid after retention by the magnet and a battery source is preserved. According to one feature of the invention, the driving means comprises a cam which supports the magnet and is slideably movable transversely to the solenoid core to move the magnet between the first and second positions. The electronic lock further comprises a second pin slideably supported and extending into the keyway to intercept the key blade when the key blade is inserted in the keyway. The cam includes a bearing surface aligned with the second pin such that as the key blade is inserted into the keyway, the second pin is driven out of the keyway and against the bearing surface of the cam, and the cam is driven transversely from the second position to the first position. The magnet is offset radially away from the solenoid core relative to a blocking surface of said cam to provide a clearance region to permit the movement of the solenoid core toward the magnet and the withdrawal of the pin from the cylindrical plug when the magnet is in the first position. The blocking surface prevents the withdrawal of the solenoid core and maintains the locking pin in engagement with the locking pin when the magnet is in the second position.